Section 4-4 is about special triangles. Special triangles are right, isosceles, and equilateral triangles. The goals of this section are too use the properties of isosceles, equilateral, and right triangles. Isosceles triangles are triangles that have two congruent sides. The two congruent sides are called the legs and the third side is the base. Right triangles are triangles with one right angle. The line opposite the right angle is the hypotenuse. Equilateral triangles have all equal sides. If a triangle is equilateral then it is equiangular.
Base angle theorem
If two sides of a triangle are congruent, then the angles opposite them are congruent.
converse of base angles theorem
If two angles of a triangle are congruent, then the sides opposite them are congruent.
Corollary theorem
If a triangle is equilateral, then it is equiangular.
Hypotenuse leg congruency theorem
If the hypotenuse and leg are congruent to another right triangles hypotenuse and leg, then the two triangles are congruent.
4-4 special triangles Pg. 236-242
Section 4-4 is about special triangles. Special triangles are right, isosceles, and equilateral triangles. The goals of this section are too use the properties of isosceles, equilateral, and right triangles. Isosceles triangles are triangles that have two congruent sides. The two congruent sides are called the legs and the third side is the base. Right triangles are triangles with one right angle. The line opposite the right angle is the hypotenuse. Equilateral triangles have all equal sides. If a triangle is equilateral then it is equiangular.
Sample problems
Helpful websites
http://www.algebralab.org/lessons/lesson.aspx?file=Trigonometry_TrigSpecialTriangles.xml
http://www.math10.com/en/geometry/triangles.html
Theorems
Base angle theorem
If two sides of a triangle are congruent, then the angles opposite them are congruent.
converse of base angles theorem
If two angles of a triangle are congruent, then the sides opposite them are congruent.
Corollary theorem
If a triangle is equilateral, then it is equiangular.
Hypotenuse leg congruency theorem
If the hypotenuse and leg are congruent to another right triangles hypotenuse and leg, then the two triangles are congruent.
practice review problems.